Enhanced viability and neural differential potential in poor post-thaw hADSCs by agarose multi-well dishes and spheroid culture

Advancements in culture technology of adipose-derived stromal/stem cells: implications for diabetes and its complications

Stem cell-based therapies exhibit considerable promise in the treatment of diabetes and its complications. Extensive research has been dedicated to elucidate the characteristics and potential applications of adipose-derived stromal/stem cells (ASCs). Three-dimensional (3D) culture, characterized by rapid advancements, holds promise for efficacious treatment of diabetes and its complications. Notably, 3D cultured ASCs manifest enhanced cellular properties and functions compared to traditional monolayer-culture. In this review, the factors influencing the biological functions of ASCs during culture are summarized. Additionally, the effects of 3D cultured techniques on cellular properties compared to two-dimensional culture is described. Furthermore, the therapeutic potential of 3D cultured ASCs in diabetes and its complications are discussed to provide insights for future research.

Systematic review on spheroids from adipose‐derived stem cells: Spontaneous or artefact state?

Three-dimensional (3D) cell cultures represent the spontaneous state of stem cells with specific gene and protein molecular expression that are more alike the in vivo condition. In vitro two-dimensional (2D) cell adhesion cultures are still commonly employed for various cellular studies such as movement, proliferation and differentiation phenomena; this procedure is standardized and amply used in laboratories, however their representing the original tissue has recently been subject to questioning. Cell cultures in 2D require a support/substrate (flasks, multiwells, etc.) and use of fetal bovine serum as an adjuvant that stimulates adhesion that most likely leads to cellular aging. A 3D environment stimulates cells to grow in suspended aggregates that are defined as "spheroids." In particular, adipose stem cells (ASCs) are traditionally observed in adhesion conditions, but a recent and vast literature offers many strategies that obtain 3D cell spheroids. These cells seem to possess a greater ability in maintaining their stemness and differentiate towards all mesenchymal lineages, as demonstrated in in vitro and in vivo studies compared to adhesion cultures. To date, standardized procedures that form ASC spheroids have not yet been established. This systematic review carries out an in-depth analysis of the 76 articles produced over the past 10 years and discusses the similarities and differences in materials, techniques, and purposes to standardize the methods aimed at obtaining ASC spheroids as already described for 2D cultures.

Mechanotransduction Regulates Reprogramming Enhancement in Adherent 3D Keratocyte Cultures

Suspended spheroid culture using ultralow attachment plates (ULAPs) is reported to effect corneal fibroblast reprogramming. Polydimethylsiloxane (PDMS), with hydrophobic and soft substrate properties, facilitates adherent spheroid formation that promotes cellular physical reprogramming into stem-like cells without using transcription factors. However, it is still unknown whether the biophysical properties of PDMS have the same effect on adult human corneal keratocyte reprogramming. Here, PDMS and essential 8 (E8) medium were utilized to culture keratocyte spheroids and fibroblast spheroids, and the reprogramming results were compared. We provide insights into the probable mechanisms of the PDMS effect on spheroids. qPCR analysis showed that the expression of some stem cell marker genes (OCT4, NANOG, SOX2, KLF4, CMYC, ABCG2 and PAX6) was significantly greater in keratocyte spheroids than in fibroblast spheroids. The endogenous level of stemness transcription factors (OCT4, NANOG, SOX2, KLF4 and CMYC) was higher in keratocytes than in fibroblasts. Immunofluorescence staining revealed Klf4, Nanog, Sox2, ABCG2 and Pax6 were positively stained in adherent 3D spheroids but weakly or negatively stained in adherent 2D cells. Furthermore, OCT4, NANOG, SOX2, KLF4, HNK1, ABCG2 and PAX6 gene expression was significantly higher in adherent 3D spheroids than in adherent 2D cells. Meanwhile, SOX2, ABCG2 and PAX6 were more upregulated in adherent 3D spheroids than in suspended 3D spheroids. The RNA-seq analysis suggested that regulation of the actin cytoskeleton, TGFβ/BMP and HIF-1 signaling pathways induced changes in mechanotransduction, the mesenchymal-to-epithelial transition and hypoxia, which might be responsible for the effect of PDMS on facilitating reprogramming. In conclusion, compared to corneal fibroblasts, keratocytes were more susceptible to reprogramming due to higher levels of endogenous stemness transcription factors. Spheroid culture of keratocytes using PDMS had a positive impact on promoting the expression of some stem cell markers. PDMS, as a substrate to form spheroids, was better able to promote reprogramming than ULAPs. These results indicated that the physiological cells and culture conditions herein enhance reprogramming. Therefore, adherent spheroid culture of keratocytes using PDMS is a promising strategy to more safely promote reprogramming, suggesting its potential application for developing clinical implants in tissue engineering and regenerative medicine.

Muse cell spheroids have therapeutic effect on corneal scarring wound in mice and tree shrews

Stem cell therapy holds promises for treating corneal scarring. Here, we use multilineage-differentiating stress-enduring (Muse) cells to study their differentiation and therapeutic potential for treating corneal injury. Muse cells were isolated from lipoaspirate, which presented biphenotype properties of both pluripotent stem cells and some mesenchymal stem cells. Muse cells expanded by about 100-fold from the initial seeding cell number to Muse spheroids with the maintenance of the Muse cell phenotype and high cell viability at 33 days by static spheroid culture. We revealed that Muse spheroids were activated by the dynamic rotary cell culture system (RCCS), as characterized by increased stemness, improved activity, and enhanced adherence. Gene and protein expression of the pluripotent markers OCT3/4, SOX2, and NANOG and of the proliferation marker KI67 in Muse spheroids cultured under RCCS were higher than those in the static group. These activated Muse spheroids enabled ready differentiation into corneal stromal cells (CSCs) expressing characteristic marker genes and proteins. Furthermore, implantation of Muse cells-differentiated CSCs (Muse-CSCs) laden assembled with two orthogonally stacked stretched compressed collagen (cell-SCC) in mouse and tree shrew wounded corneas prevented the formation of corneal scarring, increased corneal re-epithelialization and nerve regrowth, and reduced the severity of corneal inflammation and neovascularization. cell-SCC retained the capacity to suppress corneal scarring after long-distance cryopreserved transport. Thus, Muse cell therapy is a promising avenue for developing therapeutics for treating corneal scarring.

Cryopreserved Spontaneous Spheroids from Compact Bone-Derived Mesenchymal Stromal Cells for Bone Tissue Engineering

Spontaneously formed spheroids from mouse compact bone-derived mesenchymal stromal cells (CB-MSCs) possess enhanced stemness and superior plasticity. In this study, the effect of cryopreservation on viability, stemness, and osteogenic differentiation capability of spontaneous CB-MSC spheroids were investigated. CB-MSCs were isolated from mouse femur and tibia. Spheroids were cryopreserved with various concentrations of dimethyl sulfoxide (DMSO). After thawing, the number of living and dead cells was measured. The expression levels of stem cell markers and osteogenic marker genes were analyzed. The cryopreserved and noncryopreserved spheroids were transplanted in mice with a beta-tricalcium phosphate as a scaffold to evaluate the in vivo bone-forming capability. The percentage of living cells was highest when 5% DMSO was used as a cryoprotectant, confirmed by the number of dead cells. The expression of stem cell marker genes and osteogenic differentiation capability were maintained after cryopreservation with 5% DMSO. The cryopreserved spontaneous CB-MSC spheroids showed remarkable new bone formation in vivo, identical to that of the noncryopreserved spheroids even without osteogenic induction. The cryopreserved spontaneous CB-MSC spheroids retained stemness and osteogenic differentiation capability and highlight the utility of spontaneous CB-MSC spheroids as ready-to-use tissue-engineered products for bone tissue engineering.

Bioengineered three-dimensional physical constructs from quince seed mucilage for human adipose-derived mesenchymal stem cells

In this study, we aimed at fabricating a novel porous physical construct from quince seed mucilage for translational medicine applications. To achieve this goal, quince seed mucilage was extracted, molded, and freeze-dried. After being freeze-dried, the molded constructs were chemically crosslinked with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide/N-hydroxysuccinimide to maintain the mechanical integrity of the structure. The fabricated scaffolds were characterized in-depth by scanning electron microscopy, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller analysis, thermogravimetric analysis, and dynamic mechanical analysis in addition to the swelling, liquid uptake, and porosity tests. The extraction yield of mucilage was calculated to be 6.28% ± 0.40% (n = 3). The swelling ratio of crosslinked quince seed mucilage–derived scaffolds was found to be 12,677.50% ± 388.82% (n = 3), whereas the porosity of crosslinked quince seed mucilage–derived scaffolds was 83.43% ± 2.84% (n = 3). The analyses confirmed the crosslinked quince seed mucilage–derived scaffolds to be possessed interconnected, highly porous structure. Afterward, human adipose-derived mesenchymal stem cells were seeded on the crosslinked quince seed mucilage–derived scaffolds, and the cell viability on the scaffolds was assessed with 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. The MTT results revealed the scaffolds not to be possessed any cytotoxic effect on seeded cells. Human adipose-derived mesenchymal stem cells adhesion and migration on the crosslinked quince seed mucilage–derived scaffolds were also evaluated histologically using hematoxylin and eosin staining in addition to scanning electron microscopy analysis. In conclusion, we believe that crosslinked quince seed mucilage–derived scaffolds have the potential to be an alternative to routinely used polysaccharides in regenerative medicine applications.

Protective effects of human iPS-derived retinal pigmented epithelial cells on retinal degenerative disease

Background

Retinitis pigmentosa (RP) is an inherited retinal disease characterized by progressive loss of photoreceptor cells. This study aim at exploring the effect of retinal pigment epithelium (RPE) derived from human-induced pluripotent stem cell (hiPSC-RPE) on the retina of retinal degeneration 10 (rd10) mice, which are characterized with progressive photoreceptor death.

Methods

We generated RPE from hiPSCs by sequential supplementation with retinal-inducing factors and RPE specification signaling factors. The three-dimensional (3D) spheroid culture method was used to obtain optimal injectable hiPSC-RPE cells. Subretinal space transplantation was conducted to deliver hiPSC-RPE cells into the retina of rd10 mice. Neurotrophic factor secretion from transplanted hiPSC-RPE cells was detected by enzyme-linked immunosorbent assay (ELISA). Immunostaining, Western blotting, electroretinography (ERG), and visual behavior testing were performed to determine the effects of hiPSC-RPE on the retinal visual function in rd10 mice.

Results

Our data demonstrated that hiPSC-RPE cells exhibited classic RPE properties and phenotype after the sequential RPE induction from hiPSCs. hiPSC-RPE cells co-cultured with mouse retinal explants or retinal ganglion cells 5 (RGC5) exhibited decreased apoptosis. The viability and functional properties of hiPSC-RPE cells were enhanced by 3D spheroid culture. Transplanted hiPSC-derived RPE cells were identified by immunostaining with human nuclear antigen staining in the retina of rd10 14 days after subretinal space injection. The pigment epithelium-derived factor level was increased significantly. The expression of CD68, microglial activation marker, reduced after transplantation. The light avoidance behavior and ERG visual function in rd10 mice improved by the transplantation of hiPSC-RPE cells.

Conclusion

Our findings suggest that injectable hiPSC-RPE cells after 3D spheroid culture can rescue the structure and function of photoreceptors by sub-retinal transplantation, which lay the foundation for future clinical cell therapy to treat RP and other retinal degeneration diseases.

Differentiation of human umbilical cord mesenchymal stem cells into Leydig-like cells with defined molecular compounds

95% of the body's testosterone is produced by the Leydig Cells (LCs) in adult testis, and LC functional degradation can cause testosterone deficiency ultimately leading towards hypogonadism. The transplantation of LCs derived from stem cells is a very promising therapy to overcome the testosterone deficiency. The isolated umbilical cord mesenchymal stem cells (UMSCs) were identified by flow cytometry and adipogenic and osteogenic differentiation. Western blotting and reverse transcription polymerase chain reaction (RT-PCR) were used for the differentiated Leydig-like cell identification. The comparisons of the testosterone levels, gene expression levels, and cyclic adenosine monophosphate (cAMP) productions were performed through radioimmunoassay, quantitative polymerase chain reaction (qPCR), and cAMP assay kit, respectively. Here, it is stated that our isolated human UMSCs, which could positively express CD29, CD44, CD59, CD90, CD105, and CD166 but negatively express CD34 as well as could be differentiated into adipocytes and osteocytes, could be differentiated into Leydig-like cells (UMSC-LCs) using a novel differentiation method based on molecular compounds. The enrichment UMSC-LCs could secrete testosterone into the medium supernatant and produce considerable cAMP at the stimulation of luteinizing hormone (LH), and positively expressed LC lineage-typical markers LHCGR, SCARB1, SATR, CYP11A1, CYP17A1, HSD3B1, HSD17B3, and SF-1 as well as negatively expressed mesenchymal stem cell typical markers CD29, CD44, and CD105. The expression levels of NR3C4, PDGFRA, and NR3A1 in UMSC-LCs were higher than those of UMSCs and were comparable with LCs. These results illuminated that UMSCs could be differentiated into Leydig-like cells using the defined molecular compounds, which might further support MSC-derived Leydig cell transplantation therapy for testosterone insufficiency.

Around 90° Contact Angle of Dish Surface Is a Key Factor in Achieving Spontaneous Spheroid Formation

Following the discovery of the primary culture of neural stem cells, the spheroid culture has been recognized as one of the selective culture methods for somatic stem cells. Since then, various methods were reported to generate spheroids, which can enrich the potent stem cell population. However, the fundamental factors affecting spheroid formation remain unclear. In this study, we focused on the surface property of the culture dishes, in particular, hydrophobicity. Primary mouse skin culture cells were prepared with conventional two-dimensional culture, and then, the cells were transferred to culture dishes with varying hydrophobicity, which was confirmed with the water contact angles. Of these, a culture dish possessing an almost 90° water contact angle was the only one that successfully exhibited spheroid formation. The spheroid formation was spontaneous, efficient, and stable. Since this outcome was achieved with a conventional culture medium with serum, but without any additives such as epidermal growth factor, basic fibroblast growth factor, and B27, the spheroid formation from this process was not affected by serum and was also not dependent on additives. The results from immunofluorescence and quantitative real-time polymerase chain reaction testing showed the expression of embryonic stem cell markers such as SSEA-1, SOX2, OCT4, and Nanog, which confirmed that the spheroids with this method are comparable to those from other methods. This outcome was reproducible and could be applied not only to skin-derived cells but also to oral mucosa-derived cells, cortical bone-derived cells, and 3T3 cells, also suggesting the generality and robustness of this phenomenon.

Differentiation of human adipose derived stem cells into Leydig-like cells with molecular compounds

Leydig cells (LCs) are the primary source of testosterone in the testis, and testosterone deficiency caused by LC functional degeneration can lead to male reproductive dysfunction. LC replacement transplantation is a very promising approach for this disease therapy. Here, we report that human adipose derived stem cells (ADSCs) can be differentiated into Leydig-like cells using a novel differentiation method based on molecular compounds. The isolated human ADSCs expressed positive CD29, CD44, CD59 and CD105, negative CD34, CD45 and HLA-DR using flow cytometry, and had the capacity of adipogenic and osteogenic differentiation. ADSCs derived Leydig-like cells (ADSC-LCs) acquired testosterone synthesis capabilities, and positively expressed LC lineage-specific markers LHCGR, STAR, SCARB1, SF-1, CYP11A1, CYP17A1, HSD3B1 and HSD17B3 as well as negatively expressed ADSC specific markers CD29, CD44, CD59 and CD105. When ADSC-LCs labelled with lipophilic red dye (PKH26) were injected into rat testes which were selectively eliminated endogenous LCs using ethylene dimethanesulfonate (EDS, 75 mg/kg), the transplanted ADSC-LCs could survive and function in the interstitium of testes, and accelerate the recovery of blood testosterone levels and testis weights. These results demonstrated that ADSCs could be differentiated into Leydig-like cells by few defined molecular compounds, which might lay the foundation for further clinical application of ADSC-LC transplantation therapy.

Effects of storage culture media, temperature and duration on human adipose‑derived stem cell viability for clinical use

Adipose-derived stem cells (ADSCs) are mesenchymal stem cells that are often used in regenerative medicine. Maintaining ADSC viability is important, as this optimizes the curative effects of cell therapy. However, the optimal conditions for cell viability preservation remain unknown. The present study aimed to acquire a better protocol for ADSC storage by comparing the effects of various solutions and temperatures for ADSC preservation, in order to suggest the most effective methods of short-term ADSC preservation for clinical use. ADSCs from passage 2 were suspended in solutions comprising 0.9% NaCl, 10% human serum (HS) or 10% platelet-rich plasma (PRP). Suspended cells were maintained at 4°C or room temperature (~26°C) for 2, 4 and 6 h. The differentiation capacity, apoptosis and proliferation of ADSCs were determined by oil red O/alizarin red S staining, flow cytometry, and a cell counting kit-8 cell proliferation assay, respectively. In addition, reverse transcription-quantitative polymerase chain reaction and western blot analysis was performed. The results revealed that proliferation of ADSCs decreased with time. The optimal time for ADSC use was ~2 h, and 4 h was determined to be the latest time that ADSCs should be used. The 10% HS group had the highest survival rate, followed by the 10% PRP group; these two groups had higher survival rates than the 0.9% NaCl group (P<0.05). HS and PRP at 4°C enhanced the ADSC proliferation rate (P<0.05), although the difference between these two groups was insignificant (P>0.05). In conclusion, the optimal time to use ADSCs was <2 h, and should not exceed 4 h. It was recommended that, for the transportation and short-term storage of ADSCs during clinical use, they should be stored with 10% HS at 4°C to maintain ADSC viability. In addition, this was a cost-effective and safe method.

Enrichment of cancer stem cells by agarose multi-well dishes and 3D spheroid culture

As the theory of cancer stem cells (CSCs) is maturing, CSC-targeted therapy is emerging as an important therapeutic strategy and seeking the ideal method for rapid enrichment and purification of CSCs has become crucial. So far, based on the known CSC phenotypes and biological characteristics, the methods for enrichment CSCs mainly include low adhesion culture, low oxygen culture, chemotherapy drug stimulation and side population (SP) sorting but these methods cannot realize quick enrichment of the desired CSCs. Herein, we adopt a novel method that efficiently enriches a certain amount of CSCs through agarose multi-well dishes using rubber micro-molds to make cancer cells into cell spheroids (3D). These 3D cancer cell spheroids in the proportions of expression of CSC biomarkers (single stain of CD44, CD44v6 and CD133 or double stain of both CD44 and CD133) were significantly higher than those of the conventional adherent culture (2D) using flow cytometry analysis. In addition, the expression levels of stemness transcription factors such as OCT4, NANOG and SOX2 in 3D were also significantly higher than that in 2D through Western blot (WB) and quantitative polymerase chain reaction (qPCR) assays. In addition, the CSCs in 3D could form colonies with different sizes in soft agar. In conclusion, we developed a new method to enrich some kinds of CSCs, which might be a benefit for future CSC-targeted therapy studies and anti-CSC drug screening applications.

Cocktail of Chemical Compounds and Recombinant Proteins Robustly Promote the Stemness of Adipose-Derived Stem Cells

Induced pluripotent stem cells (iPSCs) from somatic cells can be reprogrammed to provide an unlimited cell resource showing great potential in disease modeling and regenerative medicine. However, the traditional method for reprogramming cells into iPSCs using genome-integrating retro- or lenti-viruses remain an obstacle for its application in clinical settings. We tried the possibility to generate pre-iPSCs from human adipose-derived stem cells (ADSCs) by nongenetic reprogramming using recombinant cell-penetrating proteins OCT4/KLF4/SOX2 (PTD-OKS) and the cocktail of small molecules (VCFZ). Our experimental results demonstrated that PTD-OKS in combination with VCFZ (VCFZ+OKS) could significantly enhance the stemness of ADSCs and easily get pre-iPSCs after 25 days treatments. The pre-iPSCs showed similar morphology to iPSCs, which were positive for alkaline phosphatase staining. Furthermore, RT-polymerase chain reaction analysis showed that VCFZ+OKS could significantly upregulate the expression of OCT4, KLF4, SOX2, and NANOG gene after 25 days treatment. And immunofluorescence staining also showed that the protein makers of pluripotent stem cell were positively expressed in VCFZ+OKS treated group. Our data suggest that nongenetic-mediated reprogramming from ADSCs may be a promising stem cell sources for cell therapy in the near future.

Engineering principles for guiding spheroid function in the regeneration of bone, cartilage, and skin

There is a critical need for strategies that effectively enhance cell viability and post-implantation performance in order to advance cell-based therapies. Spheroids, which are dense cellular aggregates, overcome many current limitations with transplanting individual cells. Compared to individual cells, the aggregation of cells into spheroids results in increased cell viability, together with enhanced proangiogenic, anti-inflammatory, and tissue-forming potential. Furthermore, the transplantation of cells using engineered materials enables localized delivery to the target site while providing an opportunity to guide cell fate in situ, resulting in improved therapeutic outcomes compared to systemic or localized injection. Despite promising early results achieved by freely injecting spheroids into damaged tissues, growing evidence demonstrates the advantages of entrapping spheroids within a biomaterial prior to implantation. This review will highlight the basic characteristics and qualities of spheroids, describe the underlying principles for how biomaterials influence spheroid behavior, with an emphasis on hydrogels, and provide examples of synergistic approaches using spheroids and biomaterials for tissue engineering applications.

Microtissues Enhance Smooth Muscle Differentiation and Cell Viability of hADSCs for Three Dimensional Bioprinting

Smooth muscle differentiated human adipose derived stem cells (hADSCs) provide a crucial stem cell source for urinary tissue engineering, but the induction of hADSCs for smooth muscle differentiation still has several issues to overcome, including a relatively long induction time and equipment dependence, which limits access to abundant stem cells within a short period of time for further application. Three-dimensional (3D) bioprinting holds great promise in regenerative medicine due to its controllable construction of a designed 3D structure. When evenly mixed with bioink, stem cells can be spatially distributed within a bioprinted 3D structure, thus avoiding drawbacks such as, stem cell detachment in a conventional cell-scaffold strategy. Notwithstanding the advantages mentioned above, cell viability is often compromised during 3D bioprinting, which is often due to pressure during the bioprinting process. The objective of our study was to improve the efficiency of hADSC smooth muscle differentiation and cell viability of a 3D bioprinted structure. Here, we employed the hanging-drop method to generate hADSC microtissues in a smooth muscle inductive medium containing human transforming growth factor β1 and bioprinted the induced microtissues onto a 3D structure. After 3 days of smooth muscle induction, the expression of α-smooth muscle actin and smoothelin was higher in microtissues than in their counterpart monolayer cultured hADSCs, as confirmed by immunofluorescence and western blotting analysis. The semi-quantitative assay showed that the expression of α-smooth muscle actin (α-SMA) was 0.218 ± 0.077 in MTs and 0.082 ± 0.007 in Controls; smoothelin expression was 0.319 ± 0.02 in MTs and 0.178 ± 0.06 in Controls. Induced MTs maintained their phenotype after the bioprinting process. Live/dead and cell count kit 8 assays showed that cell viability and cell proliferation in the 3D structure printed with microtissues were higher at all time points compared to the conventional single-cell bioprinting strategy (mean cell viability was 88.16 ± 3.98 vs. 61.76 ± 15% for microtissues and single-cells, respectively). These results provide a novel way to enhance the smooth muscle differentiation of hADSCs and a simple method to maintain better cell viability in 3D bioprinting.